Method of controlling and improving SOG etchback etcher

Abstract

A new method for improving particle level, stability of etch rate, and better etch uniformity by using a dry plasma clean to remove polymer buildup from the upper electrode and walls of an etch chamber after spin-on-glass etchback is described. An etching chamber having a lower electrode, upper electrode, and interior walls is provided. Spin-on-glass etchback is performed within the etching chamber whereby a polymer buildup forms on surfaces of chamber. A dummy wafer is placed into the etching chamber and the polymer buildup within the chamber is removed using a dry plasma cleaning process.

What is claimed is:  
     
       1. A method of removing polymer buildup from the surfaces of an etching chamber comprising: 
       providing said etching chamber in which spin-on-glass etchback is performed whereby said polymer buildup is formed on said surfaces of said chamber including an upper electrode in said chamber;  
       placing a dummy wafer into said etching chamber; and  
       removing said polymer buildup from said surfaces of said chamber including said upper electrode using a dry plasma cleaning process comprising flowing Ar at 300 to 500 sccm, flowing O 2  at 15 to 100 sccm, and flowing CF 4  at 40 to 100 sccm under a pressure of 200 to 600 mTorr and power of 500 to 1000 watts for a duration of 20 to 50 minutes.  
     
     
       2. A method according to  claim 1  wherein said polymer buildup is formed during said spin-on-glass etchback. 
     
     
       3. A method according to  claim 1  wherein said step of removing said polymer is performed after “N” lots of production wafers have undergone said spin-on-glass etchback process wherein “N” is greater than 1. 
     
     
       4. A method according to  claim 1  wherein said step of removing said polymer is performed after “N” lots of production wafers have undergone said spin-on-glass etchback process wherein “N” is between about 8 and 12. 
     
     
       5. The method according to  claim 1  wherein said dummy wafer comprises bare silicon. 
     
     
       6. A method of removing polymer buildup from the surfaces of an etching chamber comprising: 
       providing said etching chamber having an upper electrode and a lower electrode and interior walls wherein during spin-on-glass etchback said polymer buildup is formed on said upper electrode and said interior walls of said chamber;  
       placing a dummy wafer into said etching chamber; and  
       removing said polymer buildup from said surfaces of said chamber including said upper electrode and said interior walls using a dry plasma cleaning process comprising flowing Ar at 300 to 500 sccm, flowing O 2  at 15 to 100 sccm, and flowing CF 4  at 40 to 100 sccm under a pressure of 200 to 600 mTorr and power of 500 to 1000 watts for a duration of 20 to 50 minutes.  
     
     
       7. A method according to  claim 6  wherein said step of removing said polymer is performed after “N” lots of production wafers have undergone said spin-on-glass etchback process wherein “N” is greater than 1. 
     
     
       8. A method according to  claim 6  wherein said step of removing said polymer is performed after “N” lots of production wafers have undergone said spin-on-glass etchback process wherein “N” is between about 8 and 12. 
     
     
       9. The method according to  claim 6  wherein said dummy wafer comprises bare silicon. 
     
     
       10. A method of removing polymer buildup from the surfaces of an etching chamber comprising: 
       providing said etching chamber having an upper electrode and a lower electrode and interior walls;  
       placing a production wafer having a spin-on-glass layer formed thereon on said lower electrode;  
       etching back said spin-on-glass layer whereby said polymer buildup is formed on said upper electrode and said interior walls of said etching chamber;  
       removing said production wafer;  
       repeating said steps of placing said production wafer on said lower electrode, etching back said spin-on-glass layer, and removing said production wafer for “N” lots of production wafers where “N” is greater than 1;  
       thereafter, placing a dummy wafer into said etching chamber; and  
       removing said polymer buildup from said surfaces of said chamber including said upper electrode and said interior walls using a dry plasma cleaning process comprising flowing Ar at 300 to 500 sccm, flowing O 2  at 15 to 100 sccm, and flowing CF 4  at 40 to 100 sccm under a pressure of 200 to 600 mTorr and power of 500 to 1000 watts for a duration of 20 to 50 minutes.  
     
     
       11. A method according to  claim 10  wherein said “N” is between about 8 and 12. 
     
     
       12. The method according to  claim 10  wherein said dummy wafer comprises bare silicon.